DEV Community: Md Mehedi Hasan

Linux Command Cheat Sheet

Md Mehedi Hasan — Thu, 08 May 2025 10:25:27 +0000

🔗 Networking Commands

Command	Description
`ssh username@ip-address`	Login into a remote Linux machine using SSH
`ping hostname` or `ping ip`	Analyze network and host connections
`dir`	Display files in the current directory of a remote computer
`cd dirname`	Change directory to `dirname` on a remote computer
`put file`	Upload `file` from local to remote computer
`get file`	Download `file` from remote to local computer
`quit`	Logout from the remote connection

⚙️ Process Management Commands

Command	Description
`bg`	Send a process to the background
`fg`	Bring a stopped process to the foreground
`top`	Display details on all active processes
`ps`	Show the status of processes running for a user
`ps PID`	Display the status of a specific process
`pidof process`	Get the Process ID (PID) of a process
`kill PID`	Terminate a process
`nice`	Start a process with a specified priority
`renice`	Change the priority of an already running process
`df`	Show free hard disk space
`free`	Display available RAM memory

✍️ VI Editing Commands

Command	Description
`i`	Insert at cursor (goes into insert mode)
`a`	Write after the cursor (goes into insert mode)
`A`	Write at the end of the line (goes into insert mode)
`ESC`	Terminate insert mode
`u`	Undo the last change
`U`	Undo all changes to the entire line
`o`	Open a new line (goes into insert mode)
`dd`	Delete the current line
`3dd`	Delete 3 lines
`D`	Delete contents of the line after the cursor
`C`	Delete contents of the line after the cursor and insert new text (end with `ESC`)
`dw`	Delete a word
`4dw`	Delete 4 words
`cw`	Change a word
`x`	Delete the character at the cursor
`r`	Replace the character
`R`	Overwrite characters from the cursor onward
`s`	Substitute one character under the cursor and continue to insert
`S`	Substitute the entire line and begin inserting at the start of the line
`~`	Toggle the case of the character at the cursor

DevOps Learning Journey

Md Mehedi Hasan — Fri, 28 Feb 2025 15:08:06 +0000

🔹 Phase 1: Fundamentals of DevOps
✅ 1️⃣ Understand DevOps Concepts

What is DevOps?
DevOps vs Traditional IT
DevOps lifecycle (CI/CD, automation, monitoring, etc.)
✅ 2️⃣ Learn Linux & Shell Scripting

Basic Linux commands (ls, cd, grep, sed, awk, etc.)
User & file permissions
Writing Bash scripts
✅ 3️⃣ Networking & Cloud Basics

HTTP, HTTPS, FTP, DNS, Load Balancers
Basic understanding of AWS, Azure, or GCP
Virtual Machines vs Containers
✅ 4️⃣ Version Control with Git

Git basics (clone, commit, push, pull)
Branching & Merging
Working with GitHub/GitLab
🔹 Phase 2: DevOps Tools & CI/CD
✅ 5️⃣ Learn Containerization with Docker

Docker installation & basic commands
Creating and managing Docker containers
Writing Dockerfiles
✅ 6️⃣ Container Orchestration with Kubernetes

Kubernetes architecture (Pods, Deployments, Services)
Running applications on Kubernetes
ConfigMaps & Secrets
✅ 7️⃣ CI/CD with Jenkins & GitHub Actions

What is CI/CD?
Setting up a Jenkins pipeline
Automating builds with GitHub Actions
✅ 8️⃣ Infrastructure as Code (IaC) - Terraform & Ansible

Writing Terraform scripts for cloud infrastructure
Automating server configurations with Ansible
🔹 Phase 3: Advanced DevOps & Cloud
✅ 9️⃣ Monitoring & Logging

Setting up Prometheus & Grafana for monitoring
Logging with ELK (Elasticsearch, Logstash, Kibana)
✅ 🔟 Security & Performance Optimization

DevSecOps principles
Load testing with JMeter
Securing CI/CD pipelines
✅ 1️⃣1️⃣ Cloud Services & Serverless Computing

Deep dive into AWS (EC2, S3, Lambda, CloudFormation)
Deploying serverless applications
🔹 Phase 4: Real-World Projects & Certifications
✅ 1️⃣2️⃣ Hands-on Real-World Projects

Build a CI/CD pipeline for a real application
Deploy Kubernetes clusters on AWS/GCP
Automate infrastructure provisioning with Terraform
✅ 1️⃣3️⃣ Get Certified (Optional but Recommended)

AWS Certified DevOps Engineer
Kubernetes Administrator (CKA)
HashiCorp Certified Terraform Associate
💡 Bonus Tips for Success
✅ Follow DevOps blogs & YouTube channels (KodeKloud, DevOpsToolkit, etc.)
✅ Join DevOps communities (Reddit r/devops, LinkedIn groups)
✅ Contribute to open-source projects on GitHub

Computer Networking Learning Path

Md Mehedi Hasan — Tue, 22 Oct 2024 04:23:32 +0000

Here's a roadmap to help you learn computer networking from the ground up.

Phase 1: Networking Basics

This phase is all about understanding the foundational concepts.

Introduction to Networking:
- What is networking?
- Types of networks (LAN, WAN, PAN, MAN)
- Client-Server vs Peer-to-Peer networks
- Network topologies (star, bus, mesh, etc.)
Networking Devices:
- Routers
- Switches
- Hubs
- Access Points
- Modems
OSI and TCP/IP Models:
- OSI Model (7 Layers: Physical to Application)
- TCP/IP Model (4 Layers: Network Interface to Application)
- Understand encapsulation and de-encapsulation.
IP Addressing:
- What is an IP address?
- IPv4 vs IPv6
- Private vs Public IP addresses
- Subnetting basics
- CIDR (Classless Inter-Domain Routing)
MAC Addressing:
- What is a MAC address?
- MAC vs IP address
- ARP (Address Resolution Protocol)

Resources:

CompTIA Network+ Certification Guide
FreeCodeCamp: Introduction to Networking
Networking Basics by Cisco Networking Academy

Phase 2: Intermediate Networking

This phase focuses on deeper concepts that are essential to configuring and troubleshooting networks.

Subnetting:
- Subnet masks
- Calculate network, broadcast, and host addresses
- Variable Length Subnet Masking (VLSM)
Routing:
- Static vs Dynamic routing
- Routing protocols: RIP, OSPF, EIGRP, BGP
- Default gateway
Switching:
- VLANs (Virtual Local Area Networks)
- STP (Spanning Tree Protocol)
- Link Aggregation
DNS (Domain Name System):
- How DNS works (DNS records, lookup process)
- Common DNS servers (Google, Cloudflare, OpenDNS)
DHCP (Dynamic Host Configuration Protocol):
- DHCP process and how it works
- Lease times and IP pools
Firewalls and NAT:
- Types of firewalls (hardware/software, stateless/stateful)
- Network Address Translation (NAT)
- Port forwarding
Wireless Networking:
- Wi-Fi standards (802.11a/b/g/n/ac/ax)
- Wireless security protocols (WPA, WPA2, WPA3)
- Access Points and Wireless Controllers

Resources:

Cisco Packet Tracer (for practice)
SubnettingPractice.com (for subnetting exercises)
Udemy: Cisco CCNA course
Professor Messer's Network+ videos

Phase 3: Advanced Networking & Protocols

In this phase, you'll dive into the more complex protocols, network design, and security measures.

Advanced IP Addressing and Subnetting:
- Advanced VLSM, Supernetting
- Subnetting large networks
Advanced Routing Protocols:
- BGP (Border Gateway Protocol)
- MPLS (Multiprotocol Label Switching)
VPNs (Virtual Private Networks):
- Types: SSL VPN, IPSec VPN
- How VPNs work
- Site-to-Site VPN vs Remote Access VPN
QoS (Quality of Service):
- Traffic shaping
- Packet prioritization
Network Security:
- Encryption basics (Symmetric vs Asymmetric)
- Firewalls, IDS/IPS (Intrusion Detection/Prevention Systems)
- Zero Trust Architecture
- Network Security Protocols (SSL/TLS, IPsec, HTTPS)
Load Balancing and High Availability:
- Types of Load Balancing (Round Robin, Least Connections)
- Failover, Redundancy, and High Availability (HA) Concepts

Resources:

Cisco CCNP Guidebooks
O'Reilly: Network Security with OpenSSL
Networking for Dummies (Advanced Edition)

Phase 4: Hands-On Practice and Certifications

Applying what you’ve learned is key to becoming proficient. Start working with networking tools, labs, and practice exams.

Tools & Labs:
- Cisco Packet Tracer (simulated networking environment)
- GNS3 (network emulation software)
- Wireshark (network packet analyzer)
- Set up home networking lab (Routers, Switches)
Certifications (Optional but helpful for careers):
- CompTIA Network+ (Foundational level)
- Cisco CCNA (Cisco Certified Network Associate) (Intermediate)
- Cisco CCNP (Cisco Certified Network Professional) (Advanced)
- Certified Ethical Hacker (CEH) (Security focus)

By following this roadmap, you'll gain a solid understanding of computer networking, which is crucial for many areas in IT including cybersecurity, cloud computing, and DevOps.

DevOps Learning Journey: A Step-by-Step Roadmap

Md Mehedi Hasan — Mon, 21 Oct 2024 12:19:37 +0000

Starting your DevOps journey from zero can be exciting!

1. Understand DevOps Basics

Learn What DevOps Is:
- DevOps is a combination of development (Dev) and operations (Ops). It's about automating and improving the software delivery process.
- Key Concepts: Continuous Integration (CI), Continuous Deployment (CD), Infrastructure as Code (IaC), Automation, Monitoring.

Suggested YouTube Videos:

"What is DevOps? | DevOps Explained in 8 Minutes" by Simplilearn:
- Watch Here
"What is DevOps? In Simple English" by TechWorld with Nana:
- Watch Here

2. Learn the Basics of Linux

Why: Most DevOps tools run on Linux. Understanding how to use Linux command line and scripting will help you manage servers.
Focus On:
- Basic Commands
- File permissions
- Networking basics
- Bash scripting

Suggested YouTube Videos:

"Linux Full Course - Learn Linux in 8 Hours" by Edureka:
- Watch Here

3. Learn Version Control with Git

Why: Git is essential in DevOps for tracking changes and collaborating on code.
Key Topics:
- Branches, Commits, Merge, Pull, Push

Suggested YouTube Videos:

"Git & GitHub Crash Course For Beginners" by Traversy Media:
- Watch Here

4. Learn CI/CD

Why: CI/CD helps automate testing and deployment of code. Tools like Jenkins, GitLab CI, and GitHub Actions are widely used.
Focus On:
- Continuous Integration (CI)
- Continuous Deployment (CD)
- Creating pipelines

Suggested YouTube Videos:

"Jenkins Beginner Tutorial - Step by Step" by Automation Step by Step:
- Watch Here

5. Understand Infrastructure as Code (IaC)

Why: Tools like Terraform, Ansible, or CloudFormation are used to manage infrastructure in code form.
Focus On:
- Automating infrastructure setup
- Configuration management

Suggested YouTube Videos:

"Terraform Tutorial for Beginners" by KodeKloud:
- Watch Here

6. Learn About Containers and Kubernetes

Why: Containers (like Docker) are essential for packaging applications, and Kubernetes helps in managing containerized applications.
Focus On:
- Docker basics
- Kubernetes basics

Suggested YouTube Videos:

"Docker Tutorial for Beginners" by TechWorld with Nana:
- Watch Here
"Kubernetes for Beginners" by KodeKloud:
- Watch Here

7. Learn Cloud Platforms

Why: AWS, Azure, and Google Cloud are used to host applications and manage infrastructure.
Focus On:
- Compute (EC2, Azure VM)
- Storage (S3, Azure Blob)
- Networking

Suggested YouTube Videos:

"AWS Full Course - Learn AWS in 10 Hours" by Simplilearn:
- Watch Here

Recommended Learning Path:

Start with DevOps basics.
Get familiar with Linux.
Learn Git and CI/CD concepts.
Explore infrastructure automation (Terraform/Ansible).
Understand containers and orchestration (Docker, Kubernetes).
Learn about cloud platforms (AWS, Azure).

Once you’ve covered these basics, you can dive deeper into specific tools and best practices!